#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>

typedef struct
{
    unsigned int count[2];
    unsigned int state[4];
    unsigned char buffer[64];
}MD5_CTX;


#define F(x,y,z) ((x & y) | (~x & z))
#define G(x,y,z) ((x & z) | (y & ~z))
#define H(x,y,z) (x^y^z)
#define I(x,y,z) (y ^ (x | ~z))
#define ROTATE_LEFT(x,n) ((x << n) | (x >> (32-n)))


#define FF(a,b,c,d,x,s,ac) \
          { \
          a += F(b,c,d) + x + ac; \
          a = ROTATE_LEFT(a,s); \
          a += b; \
          }

#define GG(a,b,c,d,x,s,ac) \
          { \
          a += G(b,c,d) + x + ac; \
          a = ROTATE_LEFT(a,s); \
          a += b; \
          }

#define HH(a,b,c,d,x,s,ac) \
          { \
          a += H(b,c,d) + x + ac; \
          a = ROTATE_LEFT(a,s); \
          a += b; \
          }

#define II(a,b,c,d,x,s,ac) \
          { \
          a += I(b,c,d) + x + ac; \
          a = ROTATE_LEFT(a,s); \
          a += b; \
          }                                            


#define FF_T(a,b,c,d,x,s,ac)    (ROTATE_LEFT( (a + F(b,c,d) + x + ac) ,s ) + b)
#define GG_T(a,b,c,d,x,s,ac)    (ROTATE_LEFT( (a + G(b,c,d) + x + ac) ,s ) + b)
#define HH_T(a,b,c,d,x,s,ac)    (ROTATE_LEFT( (a + H(b,c,d) + x + ac) ,s ) + b)
#define II_T(a,b,c,d,x,s,ac)    (ROTATE_LEFT( (a + I(b,c,d) + x + ac) ,s ) + b)


void MD5Init(MD5_CTX* context);
void MD5Update(MD5_CTX* context, unsigned char* input, unsigned int inputlen);
void MD5Final(MD5_CTX* context, unsigned char digest[16]);
void MD5Transform(unsigned int state[4], unsigned char block[64]);
void MD5Encode(unsigned char* output, unsigned int* input, unsigned int len);
void MD5Decode(unsigned int* output, unsigned char* input, unsigned int len);


unsigned char PADDING[] = 
{
    0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 
};


void MD5Init(MD5_CTX* context)
{
    context->count[0] = 0;
    context->count[1] = 0;
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
}

void MD5Update(MD5_CTX* context, unsigned char* input, unsigned int inputlen)
{
    unsigned int i = 0, index = 0, partlen = 0;
    index = (context->count[0] >> 3) & 0x3F;
    partlen = 64 - index;
    context->count[0] += inputlen << 3;
    if (context->count[0] < (inputlen << 3))
        context->count[1]++;
    context->count[1] += inputlen >> 29;

    if (inputlen >= partlen)
    {
        memcpy(&context->buffer[index], input, partlen);
        MD5Transform(context->state, context->buffer);
        for (i = partlen; i + 64 <= inputlen; i += 64)
            MD5Transform(context->state, &input[i]);
        index = 0;
    }
    else
    {
        i = 0;
    }
    memcpy(&context->buffer[index], &input[i], inputlen - i);
}


void MD5Final(MD5_CTX* context, unsigned char digest[16])
{
    unsigned int index = 0, padlen = 0;
    unsigned char bits[8];
    index = (context->count[0] >> 3) & 0x3F;
    padlen = (index < 56) ? (56 - index) : (120 - index);
    MD5Encode(bits, context->count, 8);
    MD5Update(context, PADDING, padlen);
    MD5Update(context, bits, 8);
    MD5Encode(digest, context->state, 16);
}


void MD5Encode(unsigned char* output, unsigned int* input, unsigned int len)
{
    unsigned int i = 0, j = 0;
    while (j < len)
    {
        output[j] = input[i] & 0xFF;
        output[j + 1] = (input[i] >> 8) & 0xFF;
        output[j + 2] = (input[i] >> 16) & 0xFF;
        output[j + 3] = (input[i] >> 24) & 0xFF;
        i++;
        j += 4;
    }
}


void MD5Decode(unsigned int* output, unsigned char* input, unsigned int len)
{
    unsigned int i = 0, j = 0;
    while (j < len)
    {
        output[i] = (input[j]) |
            (input[j + 1] << 8) |
            (input[j + 2] << 16) |
            (input[j + 3] << 24);
        i++;
        j += 4;
    }
}


void MD5Transform(unsigned int state[4], unsigned char block[64])
{
    unsigned int a = state[0];
    unsigned int b = state[1];
    unsigned int c = state[2];
    unsigned int d = state[3];
    unsigned int x[64];
    MD5Decode(x, block, 64);

    unsigned int a_ff1, a_ff2, a_ff3, a_ff4;
    unsigned int b_ff1, b_ff2, b_ff3, b_ff4;
    unsigned int c_ff1, c_ff2, c_ff3, c_ff4;
    unsigned int d_ff1, d_ff2, d_ff3, d_ff4;


    unsigned int a_gg1, a_gg2, a_gg3, a_gg4;
    unsigned int b_gg1, b_gg2, b_gg3, b_gg4;
    unsigned int c_gg1, c_gg2, c_gg3, c_gg4;
    unsigned int d_gg1, d_gg2, d_gg3, d_gg4;


    unsigned int a_hh1, a_hh2, a_hh3, a_hh4;
    unsigned int b_hh1, b_hh2, b_hh3, b_hh4;
    unsigned int c_hh1, c_hh2, c_hh3, c_hh4;
    unsigned int d_hh1, d_hh2, d_hh3, d_hh4;

    unsigned int a_ii1, a_ii2, a_ii3, a_ii4;
    unsigned int b_ii1, b_ii2, b_ii3, b_ii4;
    unsigned int c_ii1, c_ii2, c_ii3, c_ii4;
    unsigned int d_ii1, d_ii2, d_ii3, d_ii4;


    /* Round 1 */
    a_ff1 = FF_T(a,     b,     c,     d,     x[0],  7,  0xd76aa478); /* 1 */
    d_ff1 = FF_T(d,     a_ff1, b,     c,     x[1],  12, 0xe8c7b756); /* 2 */
    c_ff1 = FF_T(c,     d_ff1, a_ff1, b,     x[2],  17, 0x242070db); /* 3 */
    b_ff1 = FF_T(b,     c_ff1, d_ff1, a_ff1, x[3],  22, 0xc1bdceee); /* 4 */

    a_ff2 = FF_T(a_ff1, b_ff1, c_ff1, d_ff1, x[4],  7 , 0xf57c0faf); /* 5 */
    d_ff2 = FF_T(d_ff1, a_ff2, b_ff1, c_ff1, x[5],  12, 0x4787c62a); /* 6 */
    c_ff2 = FF_T(c_ff1, d_ff2, a_ff2, b_ff1, x[6],  17, 0xa8304613); /* 7 */
    b_ff2 = FF_T(b_ff1, c_ff2, d_ff2, a_ff2, x[7],  22, 0xfd469501); /* 8 */

    a_ff3 = FF_T(a_ff2, b_ff2, c_ff2, d_ff2, x[8] , 7 , 0x698098d8); /* 9 */
    d_ff3 = FF_T(d_ff2, a_ff3, b_ff2, c_ff2, x[9] , 12, 0x8b44f7af); /* 10 */
    c_ff3 = FF_T(c_ff2, d_ff3, a_ff3, b_ff2, x[10], 17, 0xffff5bb1); /* 11 */
    b_ff3 = FF_T(b_ff2, c_ff3, d_ff3, a_ff3, x[11], 22, 0x895cd7be); /* 12 */


    a_ff4 = FF_T(a_ff3, b_ff3, c_ff3, d_ff3, x[12], 7,  0x6b901122); /* 13 */
    d_ff4 = FF_T(d_ff3, a_ff4, b_ff3, c_ff3, x[13], 12, 0xfd987193); /* 14 */
    c_ff4 = FF_T(c_ff3, d_ff4, a_ff4, b_ff3, x[14], 17, 0xa679438e); /* 15 */
    b_ff4 = FF_T(b_ff3, c_ff4, d_ff4, a_ff4, x[15], 22, 0x49b40821); /* 16 */


    /* Round 2 */
    a_gg1 = GG_T(a_ff4, b_ff4, c_ff4, d_ff4, x[1],  5,  0xf61e2562); /* 17 */
    d_gg1 = GG_T(d_ff4, a_gg1, b_ff4, c_ff4, x[6],  9,  0xc040b340); /* 18 */
    c_gg1 = GG_T(c_ff4, d_gg1, a_gg1, b_ff4, x[11], 14, 0x265e5a51); /* 19 */
    b_gg1 = GG_T(b_ff4, c_gg1, d_gg1, a_gg1, x[0],  20, 0xe9b6c7aa); /* 20 */

    a_gg2 = GG_T(a_gg1, b_gg1, c_gg1, d_gg1, x[5],  5,  0xd62f105d); /* 21 */
    d_gg2 = GG_T(d_gg1, a_gg2, b_gg1, c_gg1, x[10], 9,  0x02441453); /* 22 */
    c_gg2 = GG_T(c_gg1, d_gg2, a_gg2, b_gg1, x[15], 14, 0xd8a1e681); /* 23 */
    b_gg2 = GG_T(b_gg1, c_gg2, d_gg2, a_gg2, x[4],  20, 0xe7d3fbc8); /* 24 */

    a_gg3 = GG_T(a_gg2, b_gg2, c_gg2, d_gg2, x[9],  5,  0x21e1cde6); /* 25 */
    d_gg3 = GG_T(d_gg2, a_gg3, b_gg2, c_gg2, x[14], 9,  0xc33707d6); /* 26 */
    c_gg3 = GG_T(c_gg2, d_gg3, a_gg3, b_gg2, x[3],  14, 0xf4d50d87); /* 27 */
    b_gg3 = GG_T(b_gg2, c_gg3, d_gg3, a_gg3, x[8],  20, 0x455a14ed); /* 28 */

    a_gg4 = GG_T(a_gg3, b_gg3, c_gg3, d_gg3, x[13], 5,  0xa9e3e905); /* 29 */
    d_gg4 = GG_T(d_gg3, a_gg4, b_gg3, c_gg3, x[2],  9,  0xfcefa3f8); /* 30 */
    c_gg4 = GG_T(c_gg3, d_gg4, a_gg4, b_gg3, x[7],  14, 0x676f02d9); /* 31 */
    b_gg4 = GG_T(b_gg3, c_gg4, d_gg4, a_gg4, x[12], 20, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    a_hh1 = HH_T(a_gg4, b_gg4, c_gg4, d_gg4, x[5],  4,  0xfffa3942); /* 33 */
    d_hh1 = HH_T(d_gg4, a_hh1, b_gg4, c_gg4, x[8],  11, 0x8771f681); /* 34 */
    c_hh1 = HH_T(c_gg4, d_hh1, a_hh1, b_gg4, x[11], 16, 0x6d9d6122); /* 35 */
    b_hh1 = HH_T(b_gg4, c_hh1, d_hh1, a_hh1, x[14], 23, 0xfde5380c); /* 36 */

    a_hh2 = HH_T(a_hh1, b_hh1, c_hh1, d_hh1, x[1],  4,  0xa4beea44); /* 37 */
    d_hh2 = HH_T(d_hh1, a_hh2, b_hh1, c_hh1, x[4],  11, 0x4bdecfa9); /* 38 */
    c_hh2 = HH_T(c_hh1, d_hh2, a_hh2, b_hh1, x[7],  16, 0xf6bb4b60); /* 39 */
    b_hh2 = HH_T(b_hh1, c_hh2, d_hh2, a_hh2, x[10], 23, 0xbebfbc70); /* 40 */
    
    a_hh3 = HH_T(a_hh2, b_hh2, c_hh2, d_hh2, x[13], 4,  0x289b7ec6); /* 41 */
    d_hh3 = HH_T(d_hh2, a_hh3, b_hh2, c_hh2, x[0],  11, 0xeaa127fa); /* 42 */
    c_hh3 = HH_T(c_hh2, d_hh3, a_hh3, b_hh2, x[3],  16, 0xd4ef3085); /* 43 */
    b_hh3 = HH_T(b_hh2, c_hh3, d_hh3, a_hh3, x[6],  23, 0x04881d05); /* 44 */
    
    a_hh4 = HH_T(a_hh3, b_hh3, c_hh3, d_hh3, x[9],  4,  0xd9d4d039); /* 45 */
    d_hh4 = HH_T(d_hh3, a_hh4, b_hh3, c_hh3, x[12], 11, 0xe6db99e5); /* 46 */
    c_hh4 = HH_T(c_hh3, d_hh4, a_hh4, b_hh3, x[15], 16, 0x1fa27cf8); /* 47 */
    b_hh4 = HH_T(b_hh3, c_hh4, d_hh4, a_hh4, x[2],  23, 0xc4ac5665); /* 48 */

    /* Round 4 */
    a_ii1 = II_T(a_hh4, b_hh4, c_hh4, d_hh4, x[0],  6,  0xf4292244); /* 49 */
    d_ii1 = II_T(d_hh4, a_ii1, b_hh4, c_hh4, x[7],  10, 0x432aff97); /* 50 */
    c_ii1 = II_T(c_hh4, d_ii1, a_ii1, b_hh4, x[14], 15, 0xab9423a7); /* 51 */
    b_ii1 = II_T(b_hh4, c_ii1, d_ii1, a_ii1, x[5],  21, 0xfc93a039); /* 52 */

    a_ii2 = II_T(a_ii1, b_ii1, c_ii1, d_ii1, x[12], 6,  0x655b59c3); /* 53 */
    d_ii2 = II_T(d_ii1, a_ii2, b_ii1, c_ii1, x[3],  10, 0x8f0ccc92); /* 54 */
    c_ii2 = II_T(c_ii1, d_ii2, a_ii2, b_ii1, x[10], 15, 0xffeff47d); /* 55 */
    b_ii2 = II_T(b_ii1, c_ii2, d_ii2, a_ii2, x[1],  21, 0x85845dd1); /* 56 */

    a_ii3 = II_T(a_ii2, b_ii2, c_ii2, d_ii2, x[8],  6,  0x6fa87e4f); /* 57 */
    d_ii3 = II_T(d_ii2, a_ii3, b_ii2, c_ii2, x[15], 10, 0xfe2ce6e0); /* 58 */
    c_ii3 = II_T(c_ii2, d_ii3, a_ii3, b_ii2, x[6],  15, 0xa3014314); /* 59 */
    b_ii3 = II_T(b_ii2, c_ii3, d_ii3, a_ii3, x[13], 21, 0x4e0811a1); /* 60 */

    a_ii4 = II_T(a_ii3, b_ii3, c_ii3, d_ii3, x[4],  6,  0xf7537e82); /* 61 */
    d_ii4 = II_T(d_ii3, a_ii4, b_ii3, c_ii3, x[11], 10, 0xbd3af235); /* 62 */
    c_ii4 = II_T(c_ii3, d_ii4, a_ii4, b_ii3, x[2],  15, 0x2ad7d2bb); /* 63 */
    b_ii4 = II_T(b_ii3, c_ii4, d_ii4, a_ii4, x[9],  21, 0xeb86d391); /* 64 */

    state[0] += a_ii4;
    state[1] += b_ii4;
    state[2] += c_ii4;
    state[3] += d_ii4;
}


void MD5Transform_bk(unsigned int state[4], unsigned char block[64])
{
    unsigned int a = state[0];
    unsigned int b = state[1];
    unsigned int c = state[2];
    unsigned int d = state[3];
    unsigned int x[64];
    MD5Decode(x, block, 64);

    FF(a, b, c, d, x[0] , 7 , 0xd76aa478); /* 1 */
    FF(d, a, b, c, x[1], 12, 0xe8c7b756); /* 2 */
    FF(c, d, a, b, x[2], 17, 0x242070db); /* 3 */
    FF(b, c, d, a, x[3], 22, 0xc1bdceee); /* 4 */
    FF(a, b, c, d, x[4], 7, 0xf57c0faf); /* 5 */
    FF(d, a, b, c, x[5], 12, 0x4787c62a); /* 6 */
    FF(c, d, a, b, x[6], 17, 0xa8304613); /* 7 */
    FF(b, c, d, a, x[7], 22, 0xfd469501); /* 8 */
    FF(a, b, c, d, x[8], 7, 0x698098d8); /* 9 */
    FF(d, a, b, c, x[9], 12, 0x8b44f7af); /* 10 */
    FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
    FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], 5, 0xf61e2562); /* 17 */
    GG(d, a, b, c, x[6], 9, 0xc040b340); /* 18 */
    GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[0], 20, 0xe9b6c7aa); /* 20 */
    GG(a, b, c, d, x[5], 5, 0xd62f105d); /* 21 */
    GG(d, a, b, c, x[10], 9, 0x02441453); /* 22 */
    GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[4], 20, 0xe7d3fbc8); /* 24 */
    GG(a, b, c, d, x[9], 5, 0x21e1cde6); /* 25 */
    GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
    GG(c, d, a, b, x[3], 14, 0xf4d50d87); /* 27 */
    GG(b, c, d, a, x[8], 20, 0x455a14ed); /* 28 */
    GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
    GG(d, a, b, c, x[2], 9, 0xfcefa3f8); /* 30 */
    GG(c, d, a, b, x[7], 14, 0x676f02d9); /* 31 */
    GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], 4, 0xfffa3942); /* 33 */
    HH(d, a, b, c, x[8], 11, 0x8771f681); /* 34 */
    HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[1], 4, 0xa4beea44); /* 37 */
    HH(d, a, b, c, x[4], 11, 0x4bdecfa9); /* 38 */
    HH(c, d, a, b, x[7], 16, 0xf6bb4b60); /* 39 */
    HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
    HH(d, a, b, c, x[0], 11, 0xeaa127fa); /* 42 */
    HH(c, d, a, b, x[3], 16, 0xd4ef3085); /* 43 */
    HH(b, c, d, a, x[6], 23, 0x04881d05); /* 44 */
    HH(a, b, c, d, x[9], 4, 0xd9d4d039); /* 45 */
    HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[2], 23, 0xc4ac5665); /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], 6, 0xf4292244); /* 49 */
    II(d, a, b, c, x[7], 10, 0x432aff97); /* 50 */
    II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[5], 21, 0xfc93a039); /* 52 */
    II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
    II(d, a, b, c, x[3], 10, 0x8f0ccc92); /* 54 */
    II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[1], 21, 0x85845dd1); /* 56 */
    II(a, b, c, d, x[8], 6, 0x6fa87e4f); /* 57 */
    II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[6], 15, 0xa3014314); /* 59 */
    II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[4], 6, 0xf7537e82); /* 61 */
    II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[2], 15, 0x2ad7d2bb); /* 63 */
    II(b, c, d, a, x[9], 21, 0xeb86d391); /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}


int main()
{
    char text[] = "0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789";
    unsigned char digest[16];
    MD5_CTX md5;

    MD5Init(&md5);
    MD5Update(&md5, (unsigned char*) text, sizeof(text) - 1 );
    MD5Final(&md5, digest);

    char buf[128];
    sprintf_s(buf ,sizeof(buf), "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
        digest[0] , digest[1] , digest[2] , digest[3],
        digest[4] , digest[5] , digest[6] , digest[7],
        digest[8] , digest[9] , digest[10], digest[11],
        digest[12], digest[13], digest[14], digest[15]);

    puts(text);
    puts(buf);

    if (_stricmp("A328D4ED33E094ACB4F9835D4719C34C", buf) == 0)
        printf("ok!\r\n");

    MD5Init(&md5);
    MD5Final(&md5, digest);

    sprintf_s(buf, sizeof(buf), "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
        digest[0],  digest[1],  digest[2],  digest[3],
        digest[4],  digest[5],  digest[6],  digest[7],
        digest[8],  digest[9],  digest[10], digest[11],
        digest[12], digest[13], digest[14], digest[15]);
    puts(buf);

    return 0;
}
